1. Field of the Invention
The present invention relates to an image forming apparatus for printing a print job transmitted from an information processing apparatus, and relates to a control method for the image forming apparatus and a storage medium storing a program for executing the control method.
2. Description of the Related Art
Conventionally, a printing apparatus (e.g., image forming apparatus) is connected to a network via which a client PC is able to instruct the printing apparatus to perform printing.
An image forming apparatus heretofore used only in an office can be connected to the Internet to make it possible to instruct, from outside the office, the image forming apparatus to perform printing. In this manner, image forming apparatuses are utilized in new ways such as being used as an alternative to a facsimile machine (FAX), whereby user-friendliness is enhanced.
However, since unspecified person is able to instruct printing via the network (e.g., the Internet), a problem is posed that anonymous users are allowed to make unauthorized printing (e.g., printing of a large number of pages and printing of advertising data) with wrong intention. As a result, consumption articles (e.g., print sheets and toner) are wasted and routine printing work is hindered.
To prevent unauthorized printing, authentication is heretofore implemented, in which a user who transmits a job is identified and printing instructed by a normal user is only authorized. For example, there is IPP (Internet Printing Protocol) prescribed by RFC 2911 or the like. See, PWG IPP Work Group's Homepage, searched Sep. 3, 2008 on the Internet <URL:http://www.pwg.org/ipp/>. In the IPP, HTTP (Hyper Text Transfer Protocol) prescribed by RFC 2616 is used as a transport layer, whereby a user who instructs printing can be authenticated through, e.g., basic authentication or digest authentication in the HTTP protocol.
Another method is to use a dedicated printer driver to make authentication information contained in print data. Authentication can be performed by extracting the authentication information from the print data when the print data is analyzed by the image forming apparatus.
To prevent undesired printing, there is a technique in which received print data is temporarily stored into a storage device, and only print data suited to a printer model is actually printed (see, Japanese Laid-open Patent Publication No. 2004-164233). With this technique, even if unauthorized print data is transmitted without permission, such print data is not printed but deleted if model information contained in the print data does not match the printer. It is therefore possible to prevent sheets from being wastefully output.
However, the prior art image forming apparatus entails the following problem. Specifically, with the above described authentication method, authentication information such as a user name or a password for authentication must be set beforehand in the image forming apparatus, and therefore, a manager is needed to perform laborious work such as maintaining authentication information and matching the authentication information between a plurality of image forming apparatuses.
With the technique disclosed in Japanese Laid-open Patent Publication No. 2004-164233, in a case where print data has a size exceeding a prescribed value, it is possible to perform control to suspend the execution of printing until stored print data is selected and a print instruction to print the selected print data is given by a user. However, even if printing is instructed by a normal user, print data must be selected and a further print instruction must be given each execution of printing in a case that data size exceeds a prescribed value, which lowers user-friendliness.